"On one hand, we're pleased we're out of the woods for one outbreak," said Jane Zucker, MD, the assistant commissioner of the New York City Department of Health and Mental Hygiene. The city saw 26 measles cases in Brooklyn this spring in an outbreak officials believe centered on a public school and a wedding.

Measles symptoms typically take nearly two weeks (10-12 days) to appear after infection occurs. One two-week "incubation period" has passed with no related new cases in New York. But Zucker said experts are waiting for a second two-week period to pass before officially declaring the outbreak over.

"We do need to maintain a high level of suspicion and really stay on alert," Zucker told reporters Monday.

Officials quarantined dozens of people in San Diego and Milwaukee in response to smaller measles outbreaks in those cities

Wilma J. Wooten, MD, a public health officer for the County of San Diego Health and Human Services Agency, said officials there wound up quarantining 71 children during an outbreak that sickened 12 people in February.

The measles vaccine was first approved in 1963. Before that, the disease struck hundreds of thousands of people per year. Approximately 500 deaths were recorded in 1958, Zucker said.

Today, widespread vaccination of infants with a combination measles, mumps, and rubellavaccine has drastically cut infection rates. At least 72 cases of measles have been reported in the U.S. this year. The CDC had confirmed 64 of those cases as of April 25, most of which were linked to people who contracted measles overseas.

Overcoming Measles Myth

All of the cases in the recent outbreaks were in children or adults who had incomplete vaccinations or no vaccinations at all against measles, officials said.